/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.log4j.or;

import org.apache.log4j.Layout;

/**
 * Render {@link ThreadGroup} objects in a format similar to the information
 * output by the {@link ThreadGroup#list} method.
 * 
 * @author Ceki G&uuml;lc&uuml;
 * @since 1.0
 */
public class ThreadGroupRenderer implements ObjectRenderer {

	public ThreadGroupRenderer() {
	}

	/**
	 * Render a {@link ThreadGroup} object similar to the way that the
	 * {@link ThreadGroup#list} method output information.
	 * 
	 * <p>
	 * The output of a simple program consisting of one <code>main</code> thread
	 * is:
	 * 
	 * <pre>
	 * java.lang.ThreadGroup[name=main, maxpri=10]
	 *          Thread=[main,5,false]
	 * </pre>
	 * 
	 * <p>
	 * The boolean value in thread information is the value returned by
	 * {@link Thread#isDaemon}.
	 */
	public String doRender(Object o) {
		if (o instanceof ThreadGroup) {
			StringBuffer sbuf = new StringBuffer();
			ThreadGroup tg = (ThreadGroup) o;
			sbuf.append("java.lang.ThreadGroup[name=");
			sbuf.append(tg.getName());
			sbuf.append(", maxpri=");
			sbuf.append(tg.getMaxPriority());
			sbuf.append("]");
			Thread[] t = new Thread[tg.activeCount()];
			tg.enumerate(t);
			for (int i = 0; i < t.length; i++) {
				sbuf.append(Layout.LINE_SEP);
				sbuf.append("   Thread=[");
				sbuf.append(t[i].getName());
				sbuf.append(",");
				sbuf.append(t[i].getPriority());
				sbuf.append(",");
				sbuf.append(t[i].isDaemon());
				sbuf.append("]");
			}
			return sbuf.toString();
		} else {
			// this is the best we can do
			return o.toString();
		}
	}
}
